How McGill University is using wastewater testing to bring COVID-19 outbreaks under control


Every day, in a lab in McGill’s Macdonald Engineering Building, student urine and feces are tested for COVID-19.

Since September, the university has been testing sewage from its student residences to get a better idea of ​​the scale of the pandemic on campus and to help administrators adjust measures based on the results.

The tests detect the presence of SARS-CoV-2 in what is evacuated from every residence, whether the individuals are symptomatic or not.

“Especially now that testing rates have dropped and people are trying to get back to as close to normal as possible, this is a time when sewage testing is very valuable,” said Stephanie Loeb. , one of the civilians. engineering professors leading the project.

Daily tests inform metrics

“We call it a torpedo,” Loeb said, holding up a 3D-printed plastic sampler.

The samplers, nicknamed torpedoes in the lab because of their shape, are then stuffed with membranes and inserted into the exit pipes of residences.

Every day, the torpedoes are recovered and brought back to the laboratory for analysis.

After sample extraction and purification, each is checked for COVID-19 via polymerase chain reaction (PCR). The results then tell a story.

“It’s a representative sample of the entire population of people using the building,” Loeb said.

“If you track it over time, it can give you an idea if you’re seeing more cases in a certain building compared to others.”

Tracking consecutive days of positivity allows the university to apply different measures in its residences across an alert system: low, medium or high.

“We can really have an impact on [student] activity if we see something wrong,” said Fabrice Labeau, vice-rector for student life and learning at the university.

“We can influence their behaviors in ways that can influence the impact of an outbreak.”

Stephanie Loeb is an assistant professor of civil engineering at McGill and one of the leaders of the wastewater project. (Sarah Leavitt/CBC)

The 6th wave hits the campus

The results followed roughly the same pattern as what’s seen in the general population when it comes to the pandemic, Loeb said, with the exception of the Omicron wave during the Christmas holidays.

“We didn’t really see a big increase for Omicron over Christmas because the dorms were empty. Most of the students weren’t there,” she said, noting that McGill had implemented a hybrid system. online at the end of the holidays.

Since then, however, sewage results have indicated a steady increase in positivity.

“Most sites are rated positive most of the time right now,” Loeb said.

Labeau says the university will continue its monitoring and adjustment measures based on the results until the end of the term.

Wastewater from McGill residences, such as the new residence hall, continues to be monitored for COVID-19. (Sarah Leavitt/CBC)